1. Field of the Invention
This invention relates to a hot-melt adhesive. More particularly, it is concerned with a hot-melt adhesive having an excellent adhesive strength for the surface of an adherend containing silicon dioxide, such as glass or ceramics.
2. Description of the Prior Art
Many hot-melt adhesives are known, but they are all unsatisfactory in adhesive strength when they are used for bonding, for example, glass, ceramics, a high molecular substance or a metal to a glass surface. Their adhesive strength is so low that they easily peel off the glass surface, especially if they are used in an environment having a high degree of humidity. This is apparently due to the hydrophilic silanol groups (Si--OH) existing on the surface of glass which adsorb water molecules (H.sub.2 O) in a highly humid environment resulting in the association of those water molecules to form a water layer 2 on the surface of glass 1, as shown in FIG. 1. The water layer 2 formed in the interface between the glass 1 and a hot-melt adhesive 3 accelerates the peeling of the adhesive 3 from the glass 1.